Cardiac surgery was initially undertaken using highly invasive open procedures. A sternotomy, which is a type of incision in the center of the chest that separates the sternum was typically employed to allow access to the heart. In the past several decades, more and more cardiac operations are performed using intravascular or percutaneous techniques, where access to inner organs or other tissue is gained via a catheter.
Intravascular or percutaneous surgeries benefit patients by reducing surgery risk, complications and recovery time. However, the use of intravascular or percutaneous technologies also raises some particular challenges. Medical devices used in intravascular or percutaneous surgery need to be deployed via catheter systems which significantly increase the complexity of the device structure. As well, doctors do not have direct visual contact with the medical devices once the devices are positioned within the body.
One example of where intravascular or percutaneous medical techniques have been employed is in the treatment of a heart disorder called atrial fibrillation. Atrial fibrillation is a disorder in which spurious electrical signals cause an irregular heartbeat. Atrial fibrillation has been treated with open heart methods using a technique known as the “Cox-Maze procedure”. During this procedure, physicians create specific patterns of lesions in the left and right atria to block various paths taken by the spurious electrical signals. Such lesions were originally created using incisions, but are now typically created by ablating the tissue with various techniques including radio-frequency (RF) energy, microwave energy, laser energy and cryogenic techniques. The procedure is performed with a high success rate under the direct vision that is provided in open procedures, but is relatively complex to perform intravascularly or percutaneously because of the difficulty in creating the lesions in the correct locations. Various problems, potentially leading to severe adverse results, may occur if the lesions are placed incorrectly. It is particularly important to know the position of the various transducers which will be creating the lesions relative to cardiac features such as the pulmonary veins and mitral valve. The continuity, transmurality and placement of the lesion patterns that are formed can impact the ability to block paths taken within the heart by spurious electrical signals. Other requirements for various ones of the transducers to perform additional functions such as, but not limited to, mapping various anatomical features, mapping electrophysiological activity, sensing tissue characteristics such as impedance and temperature and tissue stimulation can also complicate the operation of the employed medical device.
In this regard, there is a need for intra-bodily-cavity transducer-based devices with improved performance and reduced complexity as compared to conventional devices.